Slot coating dies are well known for applying hot or cold melt materials (e.g., hot melt adhesives, varnishes, etc.) to substrates such as webs of printed material. A slot coating die typically comprises a slot coating die head through which the hot or cold melt material is extruded onto the substrate, as the substrate is moved past the slot coating die head.
To support the slot coating die head, support bracketry is provided. The support bracketry must allow for gross adjustment of the slot coating die relative to the substrate, to enable system set up and to allow for cleaning of the slot coating die head. Additionally, to properly apply a coating to a moving substrate, it is important to (i) provide for fine adjustment of the distance between the slot coating die head and the substrate, and (ii) provide for adjustment of the angular orientation of the slot coating die head relative to the substrate.
A prior slot coating die head structure that has been used by the assignee of the present invention is shown in FIG. 1. The prior art structure of FIG. 1 comprises a pair of outer support members "A" pivotally supported on a frame (not shown), a pair of intermediate support members "B" pivotally connected to the outer support members, and a pair of inner support members "C" pivotally connected to the intermediate support members. A die head is mounted on the front side of a support plate "D", and the support plate is connected to the backside of the pair of inner support members. The outer support members may be pivoted relative to the frame to provide for gross adjustment of the die head relative to the substrate. The intermediate support members may be pivoted relative to the outer support members, to provide for fine adjustment of the distance between the coating die head and the substrate. The inner support members may be pivoted relative to the intermediate support members, to provide for adjustment of the angular orientation of the coating die head relative to the substrate.
With the foregoing type of arrangement as shown in FIG. 1, the slot coating die is effectively supported from behind, and a number of adjustment devices "E" must be manipulated to (i) make fine adjustments of the distance between the slot coating die head and the substrate, or (ii) adjust the angular orientation of the coating die head relative to the substrate. Specifically, adjustments must be made by a "push-pull" type of action, i.e., one portion of a support member must be pulled and another portion of the support member must be pushed in order to pivot the support member to an adjusted position. Such type of action requires a number of adjustment devices "E" and requires both the push and pull types of actions to adjust a portion of the slot coating die head relative to the substrate. Adjustment of the bracketry components also sometimes necessarily includes flexing of the components.